An octanuclear compound of cerium(III), [Ce 8 (Pydc) 10 (HPydc) 4 .22H 2 O].11H 2 O ( 1 ) (Pydc=pyridine-2,6-dicarboxylate anion) was prepared under mild solvothermal conditions and its crystal structure was determined by single-crystal X-ray diffraction. Three kinds of coordination environments are observed, which include: [Ce(Pydc) 3 ], [Ce(Pydc)(H 2 O) 4 ( O,O )], and [Ce(H 2 O) 7 ( O,O )]. Each cerium atom in 1 is nine-coordinated but two different geometries are found. The Ce1 and Ce2 atoms exhibit a nearly tricapped trigonal prismatic CeN 3 O 6 geometry, while Ce3 and Ce4 possess CeNO 8 and CeO 9 coordination polyhedra, which approximate to slightly distorted mono-capped square antiprisms having 12 triangular faces. The Pydc ligands adopt tri-, tetra-, and penta-coordination modes through tridentate chelating and, μ 2 and μ 3 -bridging modes, respectively. The clusters are joined by O–H···O hydrogen bonds to generate 3D supramolecular network. Magnetic susceptibility measurements for 1 indicate that the χ m values obey the Curie-Weiss law. The overall magnetic behavior is typical for the presence of antiferromagnetic exchange coupling interactions between the cerium(III) ions.